SnAg銲錫和不同厚度的電鍍Ni/Cu UBM 之界面反應研究

Abstract

鎳在微電子工業方面有廣泛應，本論文研究共晶SnAg銲錫凸塊和三種厚度Ni/Cu金屬層在多次迴銲和固態之反應，其厚度分別為5μm-Cu/3μm-Ni、3μm-Cu/2μm-Ni、和0μm-Cu/1μm-Ni，研究結果發現150℃固態時效200小時銲錫凸塊剪力強度下降，固態時效500小時和1000小時後剪力強度改變不大，剪力強度下降肇因於Ag3Sn之介金屬化合物粗化和銲錫晶粒成長，而且，在剪力測試結果指示，對銲錫凸塊和1um-Ni反應，長時效超過200小時後破裂模式從延性轉變成脆性，導致銲錫強度突然的下降，在固態時效反應下，強度下降歸究於部分的鎳層消耗，測量鎳層在150℃之消耗速率約為0.02μm/小時1/2。

Nickel has been widely used as an under-bump metallization (UBM) material in the microelectronics industry. The reflow times and solid-state reactions between the eutectic SnAg solder bumps and three thicknesses of Ni/Cu UBM was investigated, including 5μm-Cu/3μm-Ni, 3μm-Cu/2μm-Ni, and 0μm-Cu/1μm-Ni. It was found that the shear strength of the solder bumps decreased after the solid-state aging at 150□C for 200 hours, and it did not change much after prolonged for 500 hours and 1000 hours. Aging of the Ag3Sn intermetallic compound (IMC) and grain growth of the solder are responsible for the decrease in the shear strength. Furthermore, the shear test results indicated that the fracture mode switched from ductile to brittle for the solder bumps with 1 □m of Ni after aging longer than 200 hours, causing the strength of the solder to decrease abruptly. This is attributed to the partial consumption of the Ni layer after the solid-state aging. The Ni consumption rate was measured to be 0.02μm/hr1/2 at 150℃.